Heat assisted magnetic recording heads having bilayer heat sinks

ABSTRACT

Disclosed herein is an apparatus that includes a near field transducer positioned adjacent to an air bearing surface of the apparatus; a first magnetic pole; and a heat sink positioned between the first magnetic pole and the near field transducer, wherein the heat sink includes a first and second portion, with the first portion being adjacent the near field transducer and the second portion being adjacent the first magnetic pole, the first portion including a plasmonic material, and the second portion including a diffusion blocking material.

PRIORITY

This application claims priority to U.S. Provisional Application No.61/638,080 entitled “BILAYER HEAT SINK FOR LOLLIPOP DESIGN NEAR FIELDTRANSDUCER” having docket number STL17264.01 filed on Apr. 25, 2012, thedisclosure of which is incorporated herein by reference thereto.

BACKGROUND

Heat assisted magnetic recording (HAMR) is a possible avenue forincreasing the areal density of magnetic recording. As such, advances inHAMR are ongoing.

SUMMARY

Disclosed herein is an apparatus that includes a near field transducerpositioned adjacent to an air bearing surface of the apparatus; a firstmagnetic pole; and a heat sink positioned between the first magneticpole and the near field transducer, wherein the heat sink includes afirst and second portion, with the first portion being adjacent the nearfield transducer and the second portion being adjacent the firstmagnetic pole, the first portion including a plasmonic material, and thesecond portion including a diffusion blocking material.

Also disclosed is an apparatus that includes a light source; awaveguide; a near field transducer positioned adjacent to an air bearingsurface of the apparatus; a first magnetic pole; and a heat sinkpositioned between the first magnetic pole and the near fieldtransducer, wherein the heat sink includes a first and second portion,with the first portion being adjacent the near field transducer and thesecond portion being adjacent the first magnetic pole, the first portionincluding a plasmonic material, and the second portion including adiffusion blocking material, wherein the light source, waveguide andnear field transducer are configured to transmit light from the lightsource to the waveguide and finally the near field transducer.

Also disclosed is a disc drive that includes at least one actuator armhaving a first and a second end; at least one head, wherein each arm hasa head at the first end thereof and wherein each head includes: a nearfield transducer positioned adjacent to an air bearing surface of theapparatus; a first magnetic pole; and a heat sink positioned between thefirst magnetic pole and the near field transducer, wherein the heat sinkincludes a first and second portion, with the first portion beingadjacent the near field transducer and the second portion being adjacentthe first magnetic pole, the first portion including a plasmonicmaterial, and the second portion including a diffusion blocking materialwherein the light source and the near field transducer are configured totransmit light from the light source to the near field transducer inorder to assist the magnetic writer with writing.

The above summary of the present disclosure is not intended to describeeach disclosed embodiment or every implementation of the presentdisclosure. The description that follows more particularly exemplifiesillustrative embodiments. In several places throughout the application,guidance is provided through lists of examples, which examples can beused in various combinations. In each instance, the recited list servesonly as a representative group and should not be interpreted as anexclusive list.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a pictorial representation of a data storage device in theform of a disc drive that can include a recording head constructed inaccordance with an aspect of this disclosure.

FIG. 2 is a side elevation view of a recording head constructed inaccordance with an aspect of the disclosure.

FIG. 3 is a schematic depiction of a cross section of a disclosed devicethat includes a disclosed bilayer heat sink.

The figures are not necessarily to scale. Like numbers used in thefigures refer to like components. However, it will be understood thatthe use of a number to refer to a component in a given figure is notintended to limit the component in another figure labeled with the samenumber.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanying setof drawings that form a part hereof and in which are shown by way ofillustration several specific embodiments. It is to be understood thatother embodiments are contemplated and may be made without departingfrom the scope or spirit of the present disclosure. The followingdetailed description, therefore, is not to be taken in a limiting sense.

Unless otherwise indicated, all numbers expressing feature sizes,amounts, and physical properties used in the specification and claimsare to be understood as being modified in all instances by the term“about.” Accordingly, unless indicated to the contrary, the numericalparameters set forth in the foregoing specification and attached claimsare approximations that can vary depending upon the properties sought tobe obtained by those skilled in the art utilizing the teachingsdisclosed herein.

The recitation of numerical ranges by endpoints includes all numberssubsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3,3.80, 4, and 5) and any range within that range.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” encompass embodiments having pluralreferents, unless the content clearly dictates otherwise. As used inthis specification and the appended claims, the term “or” is generallyemployed in its sense including “and/or” unless the content clearlydictates otherwise.

“Include,” “including,” or like terms means encompassing but not limitedto, that is, including and not exclusive. It should be noted that “top”and “bottom” (or other terms like “upper” and “lower”) are utilizedstrictly for relative descriptions and do not imply any overallorientation of the article in which the described element is located.

Heat assisted magnetic recording (HAMR) heads include a high magneticmoment write pole adjacent to the near field transducer (NFT) and/orheatsink. Typically, the NFT and/or heatsink are made of gold or silver,which are noble metals. The occurrence of having a noble metal adjacentto a high magnetic moment material can lead to galvanic corrosion.Galvanic corrosion is an electrochemical process in which the corrosionof one metal is enhanced due to the presence of another metal when bothmetals are in electrical contact and immersed in an electrolyte.

FIG. 1 is a pictorial representation of a data storage device in theform of a disc drive 10 that can utilize recording heads constructed inaccordance with various aspects of the disclosure. The disc drive 10includes a housing 12 (with the upper portion removed and the lowerportion visible in this view) sized and configured to contain thevarious components of the disc drive. The disc drive 10 includes aspindle motor 14 for rotating at least one magnetic storage media 16within the housing. At least one arm 18 is contained within the housing12, with each arm 18 having a first end 20 with a recording head orslider 22, and a second end 24 pivotally mounted on a shaft by a bearing26. An actuator motor 28 is located at the arm's second end 24 forpivoting the arm 18 to position the recording head 22 over a desiredsector or track 27 of the disc 16. The actuator motor 28 is regulated bya controller, which is not shown in this view and is well-known in theart.

For heat assisted magnetic recording (HAMR), electromagnetic radiation,for example, visible, infrared or ultraviolet light is directed onto asurface of the data storage media to raise the temperature of alocalized area of the media to facilitate switching of the magnetizationof the area. Recent designs of HAMR recording heads include a thin filmwaveguide on a slider to guide light to the storage media for localizedheating of the storage media. While FIG. 1 shows a disc drive, theinvention can be applied to other devices that include a transducer anda storage media, wherein the storage media is heated to facilitateswitching of bits in the storage media.

FIG. 2 is a side elevation view of a recording head constructed inaccordance with an aspect of the disclosure, and positioned near astorage media. The recording head 30 includes a substrate 32, a basecoat 34 on the substrate, a bottom pole 36 on the base coat, and a toppole 38 that is magnetically coupled to the bottom pole through a yokeor pedestal 40. A waveguide 42 is positioned between the top and bottompoles. The waveguide includes a core layer 44 and cladding layers 46 and48 on opposite sides of the core layer. A mirror 50 is positionedadjacent to one of the cladding layers. The top pole is a two-piece polethat includes a first portion, or pole body 52, having a first end 54that is spaced from the air bearing surface 56, and a second portion, orsloped pole piece 58, extending from the first portion and tilted in adirection toward the bottom pole. The second portion is structured toinclude an end adjacent to the air bearing surface 56 of the recordinghead, with the end being closer to the waveguide than the first portionof the top pole. A planar coil 60 also extends between the top andbottom poles and around the pedestal. In this example, the top poleserves as a write pole and the bottom pole serves as a return pole.

An insulating material 62 separates the coil turns. In one example, thesubstrate can be AlTiC, the core layer can be Ta₂O₅, and the claddinglayers (and other insulating layers) can be Al₂O₃. A top layer ofinsulating material 63 can be formed on the top pole. A heat sink 64 ispositioned adjacent to the sloped pole piece 58. The heat sink can becomprised of a non-magnetic material such as, for example, Au.

As illustrated in FIG. 2, the recording head 30 includes a structure forheating the magnetic storage media 16 proximate to where the write pole58 applies the magnetic write field H to the storage media 16. The media16 includes a substrate 68, a heat sink layer 70, a magnetic recordinglayer 72, and a protective layer 74. A magnetic field H produced bycurrent in the coil 60 is used to control the direction of magnetizationof bits 76 in the recording layer of the media.

The storage media 16 is positioned adjacent to or under the recordinghead 30. The waveguide 42 conducts light from a source 78 ofelectromagnetic radiation, which may be, for example, ultraviolet,infrared, or visible light. The source may be, for example, a laserdiode, or other suitable laser light source for directing a light beam80 toward the waveguide 42. Various techniques that are known forcoupling the light beam 80 into the waveguide 42 may be used. Once thelight beam 80 is coupled into the waveguide 42, the light propagatesthrough the waveguide 42 toward a truncated end of the waveguide 42 thatis formed adjacent the air bearing surface (ABS) of the recording head30. Light exits the end of the waveguide and heats a portion of themedia, as the media moves relative to the recording head as shown byarrow 82. A near field transducer (NFT) 84 is positioned in or adjacentto the waveguide and at or near the air bearing surface. The heat sinkmaterial may be chosen such that it does not interfere with theresonance of the NFT. The NFT can be any one of various types of NFTs,including, for example a nanorod type NFT, or a lollypop type NFT.

Although the example of FIG. 2 shows a perpendicular magnetic recordinghead and a perpendicular magnetic storage media, it will be appreciatedthat the disclosure may also be used in conjunction with other types ofrecording heads and/or storage media where it may be desirable toconcentrate light to a small spot.

FIG. 3 shows a disclosed apparatus. Such an apparatus includes a nearfield transducer (NFT) 320, a first magnetic pole 310, and a heat sink330. The heat sink 330 is positioned between the first magnetic pole 310and the NFT 320. The heat sink 330 includes a first portion 340 and asecond portion 350. The first portion 340 is positioned adjacent the NFT320 and the second portion 350 is positioned adjacent the first magneticpole 310.

In some embodiments, the NFT 320 can be a peg/disc type of NFT, whichcan also be referred to as a lollipop structure, a nanorod type of NFTwhich can also be referred to as a gap type of NFT, or a funnel-type NFTfor example. In some embodiments, the NFT can be a peg/disc type of NFT.The NFT acts to condense incoming light rays to a location on themagnetic media disc 305. The NFT 320 can be described as having an airbearing surface or being at the air bearing surface (ABS) of the device.The ABS is adjacent the magnetic media disc 305.

The NFT 320 can be made of a plasmonic material. Exemplary plasmonicmaterials can include, for example gold (Au), silver (Ag), copper (Cu),aluminum (Al), alloys thereof, or some combination thereof. In someembodiments, the NFT 320 can be made of, or include gold (Au), silver(Ag), or alloys thereof.

The heat sink 330, as discussed above includes a first portion 340located adjacent the NFT 320 and a second portion 350 located adjacentthe first magnetic pole. As such, disclosed heat sinks can be referredto as being bilayer heat sinks Previously utilized devices oftenexhibited issues of diffusion between the heat sinks and the magneticpole. In embodiments where the heat sink is gold (for example) and themagnetic pole is FeCo (for example), diffusion can lead to significantreliability issues for the HAMR device. Diffusion barriers have beenproposed, but often their use can have other drawbacks. For example, inembodiments where the diffusion layer is exposed to the ABS, they canincrease the NFT-pole spacing or can have an increased risk ofcorrosion. In embodiments where the heat sink was replaced by diffusionbarrier materials, the coupling efficiency of the NFT is greatlydecreased. Disclosed heat sinks offer other approaches to overcoming theissues of diffusion.

The first portion 340 of the heat sink 330 generally includes aplasmonic material. Generally, the use of plasmonic materials in thefirst portion 340 can assist in preserving the NFT coupling efficiency.Exemplary plasmonic materials can include, for example gold (Au), silver(Ag), copper (Cu), aluminum (Al), alloys thereof, or some combinationthereof. In some embodiments, the NFT 320 can be made of, or includegold (Au), silver (Ag), or alloys thereof. In some embodiments, thefirst portion 340 of the heat sink 330 can include materials such asthose disclosed in commonly owned United States Patent PublicationNumber 2011/0205863, entitled, “HAMR NFT MATERIALS WITH IMPROVED THERMALSTABILITY”, filed on Feb. 23, 2011; United States Patent Applicationhaving attorney docket number 430.17229010, entitled “HAMR NFT MATERIALSWITH IMPROVED THERMAL STABILITY”, filed on the same date as the instantapplication; and United States Patent Application having attorney docketnumber 430.17123010, entitled, “NEAR FIELD TRANSDUCERS INCLUDING NITRIDEMATERIALS”, filed on the same date as the instant application, thedisclosures of which are incorporated herein by reference thereto.

The first portion 340 of the heat sink can be deposited at the same timeas or in a single step with the NFT 320 (if they are the same material);or it can be deposited in a different step (even if they are the samematerial). In some embodiments, the first portion 340 of the heat sink340 can be deposited using various methods, including for exampleelectrodeposition, electrochemical plating methods, or physical vapordeposition (PVD) methods.

In some embodiments, the first portion 340 of the heat sink 330 can havea thickness that is chosen so as to better preserve the NFT couplingefficiency. In some embodiments, the first portion 340 of the heat sinkcan advantageously be as thin as possible so that the NPS is notincreased greatly. The NPS is the space or gap (which can be filled withan insulating material for example) between the first magnetic pole 310and the NFT 320, which can be referred to as the NFT to pole spacing(NPS). In some embodiments, the first portion 340 of the heat sink 330can have a thickness from 15 nm to 100 nm. In some embodiments, thefirst portion 340 of the heat sink 330 can have a thickness from 30 nmto 70 nm. In some embodiments, where the NFT 320 is a peg/disc type NFTand the NFT and the first portion 340 of the heat sink 330 are the samematerial, the NFT 320 can be described as having a thickness of 25 nm.In some embodiments where the first portion 340 of the heat sink 330 andthe NFT 320 are made of the same material, the two structures can bedistinguished by the dimensions of the disc with respect to theoverlying heat sink, differences in shapes, differences in deposition,or combinations thereof.

The second portion 350 of the heat sink 330 generally includes adiffusion blocking material. Generally, the use of diffusion blockingmaterials can assist in preventing diffusion between the NFT 320material and the first magnetic pole 310. Further materials propertiesthat can be considered in choosing a material for the second portion 350of the heat sink 330 can include solubility with or in adjacentmaterials, general chemical stability and stability in relation toadjacent materials, and thermal conductivity of material for example. Insome embodiments, a material that has a relatively low solid solubilitywith the NFT material, the first magnetic pole material, or both may beutilized. In some embodiments, a material that is relatively chemicallystable with the materials in the NFT, the magnetic pole, or both can beutilized. In some embodiments, materials without risks or with minimalrisks of interdifussion, intermetallic formation, or similar processescan be utilized. In some embodiments, materials that have an ability toblock or limit interdifussion between the NFT and the first magneticpole can be utilized. In some embodiments, materials that have arelatively high thermal conductivity can be utilized. This can providefor better heatsinking In some embodiments where the second heatsinklayer is not exposed to the ABS, requirement for corrosion resistancecan be relaxed. This could lead to a broader choice in materials.

In some embodiments, the second portion 350 of the heat sink 330 can bedeposited using various methods, including for exampleelectrodeposition, electrochemical plating methods, or physical vapordeposition (PVD) methods. In some embodiments, the second portion 350 ofthe heat sink 330 can include W, TiW, NiP, Rh, Ru, Ti, Ta, TiC, TiN,TiCN, TiPd, Ti₃Pd, TaC, TaN, TaCN, WN, WCN, WTiN, ZrB₂, TiB₂, HfB₂,MgB₂, VB₂, TaN, TiN, ZrN, or combinations thereof. In some embodiments,the second portion 350 of the heat sink 330 can include W, TiW, NiP, Rh,Ru, Ti, Ta, or combinations thereof. The second portion 350 of the heatsink 330 can generally span the distance from the first portion 340 ofthe heat sink 330 to the first magnetic pole 310.

Disclosed devices can include a space or gap (which can be filled withan insulating material for example) between the first magnetic pole 310and the NFT 320. This space can be referred to as the NFT-pole space orspacing, which is shown in FIG. 3 as NPS. In some embodiments, discloseddevices can have a NPS that is not greater than 50 nm. In someembodiments, disclosed devices can have a NPS that is not greater than20 nm.

Thus, embodiments of HEAT ASSISTED MAGNETIC RECORDING HEADS HAVINGBILAYER HEAT SINKS are disclosed. The implementations described aboveand other implementations are within the scope of the following claims.One skilled in the art will appreciate that the present disclosure canbe practiced with embodiments other than those disclosed. The disclosedembodiments are presented for purposes of illustration and notlimitation.

What is claimed is:
 1. An apparatus comprising: a near field transducerpositioned adjacent to an air bearing surface of the apparatus; a firstmagnetic pole; and a heat sink positioned between the first magneticpole and the near field transducer, wherein the heat sink comprises afirst and second portion, with the first portion being adjacent the nearfield transducer and the second portion being adjacent the firstmagnetic pole, the first portion comprising a plasmonic material, andthe second portion comprising a diffusion blocking material.
 2. Theapparatus according to claim 1, wherein the first portion has athickness from about 15 nm to 100 nm.
 3. The apparatus according toclaim 1, wherein the first portion has a thickness from about 30 nm toabout 70 nm.
 4. The apparatus according to claim 1, wherein the firstportion comprises Au, Ag, Al, Cu, alloys thereof, or combinationsthereof.
 5. The apparatus according to claim 1, wherein the firstportion comprises Au, Ag, Cu, Al, or combinations thereof.
 6. Theapparatus according to claim 1, wherein the second portion comprises W,TiW, NiP, Rh, Ru, Ti, Ta, TiC, TiN, TiCN, TiPd, Ti₃Pd, TaC, TaN, TaCN,WN, WCN, WTiN, ZrB₂, TiB₂, HfB₂, MgB₂, VB₂, TaN, TiN, ZrN, orcombinations thereof.
 7. The apparatus according to claim 1, wherein thesecond portion comprises W, TiW, NiP, Rh, Ru, Ti, Ta, or combinationsthereof.
 8. The apparatus according to claim 1, wherein the near fieldtransducer comprises a peg and disc.
 9. The apparatus according to claim8, wherein the first portion of the heat sink is adjacent the disc ofthe near field transducer.
 10. The apparatus according to claim 9,wherein the thickness of the disc is about 25 nm.
 11. The apparatusaccording to claim 1, wherein the apparatus has a NFT-Pole space that isdefined by the distance between the near field transducer and the writepole at the air bearing surface of the apparatus.
 12. The apparatusaccording to claim 11, wherein the NFT-Pole space is not greater thanabout 50 nm.
 13. An apparatus comprising: a light source; a waveguide; anear field transducer positioned adjacent to an air bearing surface ofthe apparatus; a first magnetic pole; and a heat sink positioned betweenthe first magnetic pole and the near field transducer, wherein the heatsink comprises a first and second portion, with the first portion beingadjacent the near field transducer and the second portion being adjacentthe first magnetic pole, the first portion comprising a plasmonicmaterial, and the second portion comprising a diffusion blockingmaterial, wherein the light source, waveguide and near field transducerare configured to transmit light from the light source to the waveguideand finally the near field transducer.
 14. The apparatus according toclaim 13, wherein the first portion of the heat sink has a thicknessfrom about 30 nm to about 70 nm.
 15. The apparatus according to claim13, wherein the first portion of the heat sink comprises Au, Ag, Cu, Al,or combinations thereof.
 16. The apparatus according to claim 13,wherein the second portion of the heat sink comprises W, TiW, NiP, Rh,Ru, Ti, Ta, TiC, TiN, TiCN, TiPd, Ti₃Pd, TaC, TaN, TaCN, WN, WCN, WTiN,ZrB₂, TiB₂, HfB₂, MgB₂, VB₂, TaN, TiN, ZrN, or combinations thereof. 17.The apparatus according to claim 13, wherein the second portioncomprises W, TiW, NiP, Rh, Ru, Ti, Ta, or combinations thereof.
 18. Adisc drive comprising: at least one actuator arm having a first and asecond end; at least one head, wherein each arm has a head at the firstend thereof and wherein each head comprises: a near field transducerpositioned adjacent to an air bearing surface of the apparatus; a firstmagnetic pole; and a heat sink positioned between the first magneticpole and the near field transducer, wherein the heat sink comprises afirst and second portion, with the first portion being adjacent the nearfield transducer and the second portion being adjacent the firstmagnetic pole, the first portion comprising a plasmonic material, andthe second portion comprising a diffusion blocking material wherein thelight source and the near field transducer are configured to transmitlight from the light source to the near field transducer in order toassist the magnetic writer with writing.
 19. The disc drive according toclaim 18, wherein the first portion of the heat sink has a thicknessfrom about 30 nm to about 70 nm and comprises Au, Ag, Cu, Al, orcombinations thereof.
 20. The disc drive according to claim 18, whereinthe second portion comprises W, TiW, NiP, Rh, Ru, Ti, Ta, orcombinations thereof.